Integrated geophysical analysis of the Sembar Formation, Central Indus Basin, as an unconventional resource

Abstract

The ever-increasing demand for new energy sources witnessed at present is leading to a shortage of oil and gas resources throughout the world. At the same time, polluting energy sources such as coal are being gradually replaced by gas, new fuel types and electricity produced by renewable methods. Unconventional shale gas reserves, relying on the presence of substantial volumes of good quality, thermally mature organic matter, are therefore crucial in shaping the economic future of multiple regions in the world. Using seismic reflection data to estimate Total Organic Carbon (TOC) in the underexplored Sembar Formation of the Qadirpur Area, Central Indus Basin, this study investigates the potential of a new unconventional resource in Pakistan. We estimate TOC based on well-log data using Passey's Δ Log R, Schmoker's, and Schwarzkopf's methods. In a second stage, thermal maturity modelling was carried out for the formations encountered in Well Qadirpur Deep-01, while focusing primarily on the Sembar Formation. Petrophysical and petroelastic properties were determined and cross-plotted to identify potential zones favourable to hydraulic fracturing. The results show calculated TOC values ranging from 2 to 4 wt% based on the multiple methods indicated above, proving that the Sembar Formation is a good to excellent unconventional oil gas play. Thermal maturity modelling further confirms that the organic matter in the Sembar Formation is mature. Our seismic based spatial distribution indicates that TOC values are particularly favourable in the lower part of the formation, which is also prone to hydraulic fracturing based on its petroelastic evaluation. This study presents a valid approach to characterise source-rock potential in sedimentary basins throughout South Asia and around the world.